A One-Round Living Greyhawk Shield Lands Regional Adventure
From the introduction:
One year ago a tomb was opened and a powerful artifact called "Truth" was stolen. Soon thereafter an enigmatic group of prophets gave vision of a wretched sea demon summoned with this artifact to wreck havoc upon the Shield Lands. The race to recapture this relic and stop the summoning has ended abruptly; the Shield Lands have lost. Truth has opened, the demon has arrived, the Eldritch Wave bleeds.